The present invention relates to an intake manifold of an outboard motor.
A multiple-cylinder engine mounted on an outboard motor or the like is provided with an intake manifold (or merely a manifold) for distributing intake air, the flow of which is regulated by a throttle body, to the respective cylinders of the engine. An intake manifold made of aluminum alloy has been normally employed, and an intake manifold made of synthetic resin has not been utilized till these days. However, it is initially adopted by the applicant of the subject application for forming a portion of the intake manifold downstream side of a throttle body of an intake device.
In many cases, the intake manifold is equipped with outfits such as filters, pumps, etc. A hose, a wire harness and the like provided among the outfit are fixed by clamps made of metal sheet or resin attached to the intake manifold by means of bolts.
However, the intake manifold made of aluminum alloy is heavy in weight and becomes larger in size as the displacement of the engine increases. Further, if the number of the cylinders of the engine increases, the number of branches thereof increases to thereby increase the weight of intake manifold.
On the other hand, if clamps are provided separately from the intake manifold, the number of parts and the number of assembling steps will be disadvantageously increased. In addition, in a case where it is necessary to provide screw holes in the intake manifold for attaching the clamps, the manufacturing cost of the intake manifold will be disadvantageously pushed up.
Further, in a certain arrangement, the intake manifold is also mounted with an engine hook for suspending an engine by a crane, for example. In another arrangement, the intake manifold is provided with a support boss for supporting an outboard motor at a time of being pushed over sideways.
On the other hand, as the intake manifold made of an aluminum has a high thermal conductivity, an insulator made of resin has been utilized for preventing heat from being transmitted at a time when a part such as delivery pipe is mounted.
However, an intake manifold made of resin has a rigidity lower than that of the aluminum intake manifold, and moreover, in a case where an outfit such as vapor separator having a relatively heavy weight is fixed to the resin intake manifold at two or three portions, it is difficult for the resin intake manifold to withstand against a vibration from the engine, thus being inconvenient.
Furthermore, in an arrangement in which the resin intake manifold is directly mounted to the engine hook, the resin intake manifold may not withstand against the weight of the engine and may be damaged when the engine is suspended.
Still furthermore, in an arrangement in which the support boss for supporting the outboard motor in a state of being pushed over sideways is provided for the resin intake manifold, it is difficult for the intake manifold to sufficiently support the outboard motor because of its heavy weight.
On the other hand, in a case where parts such as delivery pipe and the like are mounted to the intake manifold made of aluminum alloy, the use of resin insulator increases the number of parts or members, thus being inconvenient in economical point, assembling working and so on.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide an intake manifold for an outboard motor capable of reducing weight and cost and improving operational performance or operating property.
This and other objects can be achieved according to the present invention by providing an intake manifold of an outboard motor which is mounted with a multiple-cylinder engine and in which intake air is distributed by the intake manifold to respective cylinders of the engine, the intake manifold being formed of synthetic resin and comprising:
a surge tank; and
a branch including a plurality of branch sections extending from the surge tank to the respective cylinders of the engine,
the surge tank and the branch constituting an intake manifold body which is divided along a flow direction of the intake air flowing in the branch sections.
In a preferred embodiment, the intake manifold body is fixed to the engine directly at one portion and is fixed thereto, at another portion, through a throttle body to which a bracket is connected, and the intake manifold body has mating surfaces between the intake manifold body and the engine and between the intake manifold body and the throttle body, and sealing means are formed to the mating surfaces. Each of the sealing means is composed of a groove formed to the mating surface and an O-ring fitted to the groove. The bracket is formed with bolt holes in shape of slots.
The intake manifold body is provided with a plurality of reinforcement ribs extending in longitudinal direction thereof.
The divided intake manifold body is joined together by a vibration welding method.
The intake manifold body is provided with a hose clamp, the hose clamp is divided into halves, which are formed integrally with the divided portions of the intake manifold body, respectively, so that the divided halves take a form of a clamp when the divided portions of the intake manifold body are coupled together.
At least four attachment bosses for fixing an outfit of an outboard motor is provided on a surface of the intake manifold body on the side of the engine and the outfit is fixed to the attachment bosses. A mounting section of an engine hook for suspending the engine is arranged between an intake manifold fixing bosses provided at the engine and an interior of the intake manifold body so as to be fastened together by a bolt for fixing the intake manifold body.
A support boss used at a time of disposing an outboard motor to be sideways is disposed at substantially a central portion of the branch in a protruded manner. A delivery pipe constituting a fuel supply device is directly attached to the intake manifold body.
Further, it is to be noted that the term xe2x80x9cintake manifoldxe2x80x9d used in the present specification generally means an intake manifold body including other portions, but may be, in some portions, used as an intake manifold unit, for example, including the intake manifold body.
As mentioned above according to the present invention, it is possible to reduce the weight of the intake manifold, to decrease intake air resistance, improve air filling efficiency and to reduce cost.
Further, in the preferred embodiments, it is possible to improve attachment rigidity to thereby improve the durability of the intake manifold. Moreover, it is possible to seal the surfaces of the intake manifold through which the intake manifold is coupled to the throttle body and the engine, respectively.
Moreover, since bolt holes of the brackets are formed to have long hole (slot) shapes, the deformation of the intake manifold can be absorbed by the bolt holes.
Furthermore, the location of a plurality of reinforcement ribs extending in longitudinal direction at the intake manifold makes it possible to improve the rigidity of the intake manifold and to prevent salt from adhering to the intake manifold even if seawater enters the outboard motor.
Further, since divided segments of the intake manifold are coupled to and integrated with each other by a vibration welding method, it is possible to obtain high coupling strength.
Additionally, the divided hose clamp halves are formed integrally with the divided segments of the intake manifold, respectively, so that the halves take a form of a clamp when the divided segments of the intake manifold are coupled together. It is, therefore, possible to reduce the number of parts and the number of assembly steps.
Furthermore, the location of the mounting bosses at, at least, four portions and the outfit such as vapor separator is secured, so that the oscillation (resonation) of the outfit due to the engine vibration can be suppressed effectively, thus improving the durability of the intake manifold.
Since the mounting portion of the engine hook is disposed and clamped between the intake manifold fastening boss and the inside portion of the intake manifold, any load is not applied to the intake manifold at a time when the engine of the outboard motor is suspended.
The location of the support bosses makes it possible to sufficiently support the outboard motor at a time when it is mounted in a horizontally falling state.
Furthermore, the direct mounting of the delivery pipe to the intake manifold can reduce the parts or members to be assembled and the assembling workability can be hence improved.
The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.